The research has the following objectives: 1. To develop a family oriented model of diagnosis and outreach intervention for failure to thrive infants and their families. 2. To assess the effectiveness of this treatment model through objective measures the physical and psychological progress of these infants and their families. 3. To identify the features of parent-child interaction which best predict physical and psychological progress. Failure to thrive infants and their family will receive a comprehensive care pattern organized in three separate phases, entry, hospitalization, and aftercare and managed by an interdisciplinary team. This team approach will facilitate family involvement in the diagnostic and treatment process and coordination between medical and psychosocial services. Following hospitalization, all families will receive supportive services including the services of a homemaker and health aide, medical and nursing care. The study group will also receive a family oriented mental health intervention focused on the remediation dysfunctional family interactions and reinforcement of adaptive features of parent infant relationships. The effectiveness of treatment will be evaluated through detailed observations of parent-child interaction and systematic follow up of infants' physical growth, intellectual, social, and family functioning.